Normally line printers are independent of display screen terminals. A line printer is a printer which is furnished a line of print data at a time. The entire line of print is usually buffered because the line of print data is sent to the printer at very high speeds compared to the speed of operation of the printer. Once the data has been transferred, the line printer performs the printing operation at its own speed and then signals, usually by way of an interrupt, that it has finished printing the line. Line printers can attach to the same interface as display screen terminals but heretofore none have been known to be attached to a display screen terminal itself where the display screen terminal still functions in its normal manner. Display screen copier printers; however, are known to be attached to display screen terminals; for example, as in commonly assigned copending application, Ser. No. 144,499 by J. Regehr filed 4/28/80. The present invention modifies the display screen printer attachment so as to enable the display screen printer to operate as a line printer. This modification provides a line printer at a very low cost because as with the display screen copier printer, the controls and timing circuitry of the display screen terminal are used thereby eliminating the cost of such circuitry. Also storage in the display screen terminal is used as the print line buffer and the need for duplicating such storage is also eliminated.